The present invention relates to a semiconductor light emitting device of a lamp type in which a light emitting device chip is molded in a resin. More particularly, the present invention relates to a semiconductor light emitting device in which penetration of wax during soldering and water after soldering between a resin plastic package and a lead is prevented from occurring.
Conventionally a semiconductor light emitting device has been fabricated in such a manner that a light emitting device chip (hereinafter referred to as LED chip) 3 having a semiconductor layered structure is bonded to a top end of a first lead 1 made of aluminum or the like, one electrode is connected to the first lead, the other electrode is connected to a second lead 2 by a gold wire 4 or the like and such an assembly is enclosed with a package 6 made of resin transparent to light of the LED chip 3 as shown in FIG. 9. This resin package 6 is usually formed by casting in which an assembly is immersed in resin filling a receptacle in the shape of a dome and the package 6 is molded into a form whose top is like a dome so that the light can be collected. For this reason, the whole surface of the package 6 is fabricated smooth with neither a recess/protrusion profile on the surface nor inclusion of impurities therein.
A resin package of a semiconductor light emitting device of this kind has heretofore been fabricated with epoxy resin in its greater part, wherein a heat resistant filler or the like cannot be mixed into the package since light is required to transmit the package with ease, as described above. Therefore, a heat resistance of the package is as poor as it can withstand at a temperature of the order of 100 to 140.degree. C. at the highest. As a result, when a light emitting device is subjected to soldering, heat which reaches a lead degrades portions in the bottom side of the package 6, which the leads 1, 2 contact with, especially near a soldering point, as shown in FIG. 9, so that gaps 9 are formed between the leads and the package 6. There arise problems that flux or the like penetrate into the interior through the gaps during soldering and as a result, the leads are subjected to corrosion and a LED chip 3 and the like are also corroded. Besides, such gaps 9 between the leads 1, 2 and the package 6 which have occurred during soldering are not restored to the former condition after the soldering and when the device is in use later, there arises penetration of water, which corrodes the leads 1, 2, the LED chip 3 and the like, so that a problem arises that reliability is reduced.